1. REPTILE NOTES

4. REPTILES
The lifestyles of most reptiles have major adaptations for living on land.
For example, the chuckwalla, which is a lizard common to the deserts of the southwestern United States, can survive when temperatures get over 104 degrees and during arid conditions when there is little or no rain.

6. REPTILES
To survive, chuckwallas disappear below ground and aestivate (becoming dormant during the summer).
He will not come out until March, when rain falls.
He will find water and drink, storing water in large reservoirs under the skin.
If threatened, a chuckwalla will hide in the nearest rock crevice.
It will inflate its lungs with air, making it “fatter” and press up against the rock.
Friction of its body scales make him nearly impossible to dislodge.

8. EXTERNAL STRUCTURE AND MOVEMENT
The skin of reptiles has no respiratory function.
Their skin is thick, dry, and contains keratin.
Reptile skin also secretes pheromones that function in sex recognition and defense.

9. EXTERNAL STRUCTURE AND MOVEMENT
All reptiles periodically shed the outer layer of skin in a process called ecdysis.
This process usually begins in the head region and the skin usually comes off in one piece.

10. EXTENAL STRUCTURE AND MOVEMENT
Chromatophores in reptiles are similar to those in amphibians.
Cryptic coloration, mimicry, and aposematic coloration occur in reptiles.

11. Support and Movement
The reptile skeleton has a lot of bone to provide greater support.
The skull is longer than an amphibian skull.
They also have a plate of bone, the secondary palate, that partially separates the nasal passages from the mouth cavity.

12. Support and Movement
Reptiles have more cervical vertebrae than amphibians do.
The first two cervical vertebrae, the atlas and axis, provide greater freedom of movement for the head.
The atlas allows nodding and the axis allows rotation of the head.

13. Support and Movement The ribs of reptiles are also different.
For instance, the ribs of snakes have muscular connections to large belly scales to help with movement.
The cervical vertebrae of cobras have ribs that may be flared to show aggression.

14. Support and Movement
The tail vertebrae of many lizards have a vertical fracture plate.
When a lizard is grasped by the tail, these vertebrae can be broken, and a portion of the tail is lost.
Tail loss, or autotomy, is an adaptation that allows a lizard to escape from a predator’s grasp, or the disconnected piece of tail may distract a predator from the lizard.
The lizard will later regenerate the lost portion.
Movement in reptiles is similar to salamanders.

16. NUTRITION AND DIGESTIVE SYSTEM
Most reptiles are carnivores, but turtles will eat almost anything organic.
The tongues of turtles and crocodiles do not come out and are helpful for swallowing.
Some lizards and the tuatara have sticky tongues for capturing prey.
The tongue extension of chameleons exceeds their own body length.

19. NUTRITION AND DIGESTIVE SYSTEM
The most remarkable adaptation of snakes involve the changes in their skull for feeding.
The bones of the skull and jaws loosely join and can spread apart to ingest prey much larger than a normal head size.
Each half of the upper and lower jaws can move independently of each other.

21. NUTRITION AND DIGESTIVE SYSTEM
Teeth that point backward prevent prey escape and help force the food into the esophagus.
The glottis, or respiratory opening, is far forward in the mouth so the snake can breathe while slowly swallowing its prey.

23. NUTRITION AND DIGESTIVE SYSTEM
Vipers have hollow fangs.
These fangs connect to venom glands that inject venom when the viper bites.

24. NUTRITION AND DIGESTIVE SYSTEM
The upper jaw bone of vipers is hinged so that when the snake’s mouth is closed, the fangs fold back along the upper jaw.
When the mouth opens, the upper jaw bone rotates and causes the fangs to swing down.
Because the fangs project outward from the mouth, vipers may strike at objects of any size.

26. NUTRITION AND DIGESTIVE SYSTEM
Rear-fanged snakes have grooved rear teeth.
Venom is sent along these grooves and into the prey to quiet them during swallowing.
These snakes usually do not strike, and most are harmless to humans.

27. NUTRITION AND DIGESTIVE SYSTEM
Coral snakes, sea snakes, and cobras have fangs that rigidly attach to the upper jaw.
When the mouth is closed, the fangs fit into a pocket in the outer gum of the lower jaw.
Some cobras “spit” venom at their prey.
If not washed from the eyes, the venom can cause blindness.

30. NUTRITION AND DIGESTIVE SYSTEM
Venom glands are modified salivary glands.
Most snake venoms are mixtures of neurotoxins and hemotoxins.
The venoms of coral snakes, cobras, and sea snakes are primarily neurotoxins that attack nerve centers and cause respiratory paralysis.
The venoms of vipers are primarily hemotoxins that break up blood vessels attack blood vessel linings.

32. CIRCULATION, GAS EXCHANGE, TEMPERATURE REGULATION
The circulatory system of reptiles is similar to amphibians.
Because reptiles are larger than amphibians, their blood must travel under higher pressure to reach distant body parts.

33. CIRCULATION, GAS EXCHANGE, TEMPERATURE REGULATION
Like amphibians, reptiles have 2 heart atria that are completely separated and a ventricle that is incompletely divided.
Blood low in oxygen enters the ventricle from the right atrium, leaves the heart and goes to the lungs.
Blood high in oxygen enters the ventricle from the lungs and leaves through a left and right artery.

35. CIRCULATION, GAS EXCHANGE, TEMPERATURE REGULATION
When turtles go into their shells, their method of lung ventilation does not work.
They also stop breathing during diving.
During periods of apnea (no breathing), blood flow to the lungs is limited, which conserves energy and allows more efficient use of the oxygen supply.

36. Gas Exchange
Reptiles exchange gases across internal surfaces to avoid losing large amounts of water.
They do have a larynx, but usually not vocal cords.
Lungs are divided into spongy, connected chambers.
These chambers provide a large surface area for gas exchange.

37. Gas Exchange
The ribs of turtles are a part of their shell, so movements of the body wall that have ribs attached is impossible.

38. Temperature Regulation
Unlike aquatic animals, terrestrial animals may face temperature extremes that are not good for their life.
Temperature regulation is very important for animals that spend their entire lives out of water.
Most reptiles use external heat sources for temperature regulation, and are ectothermic.
Brooding Indian pythons, however, can use their metabolism to increase temperature.
Female pythons will coil around their eggs and elevate their body temperature as much as 45 degrees above the air temperature.

40. Temperature Regulation
Some reptiles can survive wide temperature fluctuations ( degrees).
To sustain activity, body temperatures have to be within a certain range ( ).
If that is not possible, the reptile will seek a retreat where body temperatures can be in this range.

41. Temperature Regulation
Most temperature regulations of reptiles are behavioral, especially in lizards.
To warm itself, a lizard places itself at right angles to the sun’s rays, often on a warm surface, facing the sun.
It then presses its body to the surface to absorb heat by conduction.
To cool itself, a lizard places its body parallel to the sun’s rays, seeks shade or burrows, or will extend its legs and tail to reduce contact with warm surfaces.
In hot climates, many reptiles are nocturnal.

43. Temperature Regulation
As temperatures rise, some reptiles begin panting, which releases heat through evaporation.
Marine iguanas divert blood to the skin while basking in the sun and warm up quickly.
When diving into cool waters, however, marine iguanas reduce heart rate and blood flow to the skin, which slows heat loss.
Chromatophores also help temperature regulation.

46. Temperature Regulation
In temperate regions, many reptiles handle cold winter temperatures by entering torpor (decreased activity in daily life).
Reptiles that are usually solitary may migrate to a common site called a hibernaculum, to spend the winter.
Heat loss from individuals in a hibernacula is reduced because of clumping together.

48. Temperature Regulation
Unlike true hibernators, a reptile body temperature in torpor is not regulated, and if the winter is too cold or the retreat too exposed, they will freeze and die.
Death from freezing is a major cause of mortality for temperate reptiles.